1. Field of the Invention
This invention relates to binary deflocculating mixtures useful in reducing viscosity of kaolin slurries.
2. Description of the Prior Art
Kaolin, a clay which is essentially a hydrated aluminum silicate, is a well known article of commerce having varied uses. For example, kaolin is used as a filler in the body of paper and as a component of paper coatings. For such and other uses, kaolin is generally shipped as a 70% by weight aqueous slurry in tank cars and tank wagons. It is important to ensure that the slurry is a liquid, freely pumpable and pourable slurry so that it can be handled with no difficulty throughout slurry formation, shipping and use. One problem which arises when kaolin slurries are shipped in this manner, especially during summer months, is that slurry temperatures rise considerably thus increasing viscosity to undesirable levels which interfere with handling. In attempts to control viscosity, dispersants or deflocculating agents have been employed such as sodium polyacrylate, sodium metasilicate, tetrasodium pyrophosphate and other complex polyphosphates. Sodium polyacrylate is the deflocculant of choice; however, it is the most expensive. The silicates, although less expensive than sodium polyacrylate are less effective on a weight basis. With respect to both, kaolin slurry viscosities tend to rise over a period of time, especially in the presence of elevated temperatures.